This application claims the priority of Korean Patent Application No. 2003-89356 filed on Dec. 10, 2003, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to an electronic display device, and more particularly, to a display device that can selectively display two-dimensional (2D) and three-dimensional (3D) images.
2. Description of the Related Art
Generally, to display a 3D image, binocular parallax is used. To display a 3D image using binocular parallax, either a stereoscopy method, wherein glasses are required, or an autostereoscopy method, wherein no glasses are required, have conventionally been used. Stereoscopy can require the use of polarized glasses or liquid crystal shutter glasses. Autostereoscopy uses a lenticular display, a parallax barrier screen, or a parallax illumination.
Stereoscopy is mainly used when many people are viewing a 3D image, such as in a theater using a polarized projector. Autostereoscopy, on the other hand, is mainly used when a small group of people are viewing an image, such as for personal use, display for a game, in a home TV set, in an exhibition display, etc.
The principle of 3D display using the parallax illumination which is an autostereoscopy method, is disclosed in U.S. Pat. No. 4,717,949, entitled “Autostereoscopy Display with Illuminating Lines and Light Valve.”
FIG. 1 is a perspective view of a display device according to the parallax illumination method disclosed in U.S. Pat. No. 4,717,949.
As depicted in FIG. 1, a display device implementing the parallax illumination method comprises a liquid crystal display 12 on which an image is displayed and an illumination plate 14, a front surface of which has a stationary barrier 16 having a plurality of slits 18 formed at a periodic interval on the back of the stationary barriers 16.
When light is emitted from a backlight mounted in the illumination plate 14, the illumination plate 14 becomes a backlight for the 3D image that irradiates light having stripe forms by passing through the plurality of slits 18 between the barriers 16. Pixels of odd-numbered columns of the LCD 12 display a left eye image observed by the left eye and the pixels of even-numbered columns display right eye image observed by right eye, thus obtaining a three dimensional image.
This method can only display three dimensional images. Therefore, since movies with 3D contents are relatively rare, consumers do get much use out of this device. Accordingly, there is a need to develop a display device capable of switching back and forth from 2D to 3D images as required.
FIG. 2 is a cross-sectional view of an autostereoscopic display disclosed in U.S. Pat. No. 6,157,424, which is a typical display unit that can display both 2D and 3D images.
The autostereoscopic display depicted in FIG. 2 has a structure that employs a liquid crystal shutter 10 which mounted behind a LCD 62, instead of stationary barriers 16. In this structure, the backlight can be used selectively as a 2D backlight that generally uniformly irradiates light and a 3D backlight that irradiates light of stripe form spaced apart with a predetermined distance by regionally controlling the permeability distribution of light generated from a backlight by a liquid crystal shutter 10 using an electrical signal.
The autostereoscopic display can easily alternate between 2D and 3D mode, however, a liquid crystal shutter 10 must be disposed behind the LCD 62. That is, two glass panels have to be used, thereby increasing the overall thickness of the LCD. Also, high power consumption is required to produce both 2D and 3D images.